import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Scanner;

public class Test10 {
    public static void main(String[] args) {
        int[] arr = {19,28,37,46,50};
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        int i = 0;
        while(num !=arr[i]) {
            i++;
            if (i >= arr.length) {
                System.out.println("不存在");
                break;
            }
            if (num == arr[i]) {
                System.out.println(i);
                break;
            }
        }
    }
}
